My old Reanult 5 needed front disks every 18 months - about 4000 miles. This was due to flaking rust at the inner and outer swept area of the disks. I put it down to very little use of the brakes in my short commute.
The current owner, who does lots more miles has no problem at all with them.
Martin
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It obviously depends on your driving style. I've always found that when the pads have been changed once, the disks wear below their limit before the replacement set of pads. So I reckon on 1.5x to 2.0x the life of brake pads.
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I've just replaced the front discs - 14yrs and 96,000m old; and pads - done 43,000m, on our nearly 17yr old Focus. Pushed a few mls of brake fluid out of the bleed nipple of the 17yr old caliper to inspect it, clear honey colour, no gunk. Pipes and seals are well made these days; the only maintenance has been rust removal every 20,000m or so as mentioned in my post above about its predecessor.
So I reckon 2 x life of pads. The disc still looked pretty robust but the inner pads were nearly down to the backing.
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The front disks on our 2003 Yaris were replaced with non OE ones in 2006 by me due to corrosion (prior owner lived near the sea). The replacements are like new 11 years later.
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So I reckon 2 x life of pads. The disc still looked pretty robust but the inner pads were nearly down to the backing.
My experience too and seems to be about right on many vehicle types, just had the third set of drive axle brake pads fitted to my lorry and the discs were changed at the same time, 685,000kms, the other discs are all originals.
I don't bother doing anything to brake discs to extend thier life on my cars, save paint the non friction surfaces black so they don't look quite so unsightly rusty through the wheels.
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In the old asbestos days, pads and linings used to wear out long before disks or drums. Now, if anything, it's the other way round.
I have related before being given a pool car about 30 years ago (it was an F-reg Pug 309) with only 16K on the clock, and with a 100-mile drive ahead of me, finding the pads were so worn that they sounded like metal on metal. I used the gears as much as I could to avoid the din - luckily most of the journey was motorway.
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In the old asbestos days, pads and linings used to wear out long before disks or drums. Now, if anything, it's the other way round.
I have related before being given a pool car about 30 years ago (it was an F-reg Pug 309) with only 16K on the clock, and with a 100-mile drive ahead of me, finding the pads were so worn that they sounded like metal on metal. I used the gears as much as I could to avoid the din - luckily most of the journey was motorway.
In most cases in the old days, the rear brake linings rarely needed replacing, usually because they were not adjusted properly/if ever/or unless they were coated in brake fluid, as the seals on rear cylinders never lasted long.
in fact most I come across, all cylinder seals had a short lifetime and as mentioned I reckon disks lasted twice as long as pads depending on use....
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When discs and pads are replaced its important that the mechanic cleans the hub face to ensure good seating of the new disc and also the carrier, fitting a new pad fitting kit if not supplied with the pads. Similarly its important to change your brake fluid when it gets to 3% as although brake fade from DOT 4 brake fluid is less of a problem than older DOT 3 the moisture which accures in the brake fluid due to it being hydroscopic aids corrosion within the caliper. This can lead to a sticking or siezed caliper resulting in one pad being permenantly in contact with the disc leading to overheating and premature wear. We see loads of vehicles at the garage where a lack of servicing of the braking system or poor fitting leads to early replacement. Its the same with fitting "white box" parts on your brakes. Some people want to spend as little as possible on their brake service then put their most valuable possessions in the car and finally not consider the extra fuel they burn driving along with sticky brakes. If you buy your own brakes from a factors to get a mate down the pub to fit then at least buy quality parts and remember some of the manufacturers also make varying quality grades of pads from within their own range of brakes. Ask the factors for their advice on a particular brand. We have an ex lightning pilot as a customer who got 65K out of his first set of front pads on his Volvo V70. I suspect he had his high spill thrills when he was in the RAF !!
(Hence how you drive the car is a major influence on how your tyres and brakes wear as well as quality of the parts nad who actually fits them)
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Similarly its important to change your brake fluid when it gets to 3% as although brake fade from DOT 4 brake fluid is less of a problem than older DOT 3 the moisture which accures in the brake fluid due to it being hydroscopic aids corrosion within the caliper.
It may be hygroscopic but modern brake seals and reservoir design ensure that no accrual can take place because there is virtually no contact with either water or moisture-laden air. This is why the advice to change brake fluid every two years is an anachronistic absurdity perpetuated by unscrupulous/ignorant garages. As far as I am aware, no-one has researched how rapidly modern brake fluid detriorates in a modern car. I guess the garage trade would be fearful of its results.
The ordinary motorist will never get their brake fluid to anywhere near its boiling point. Even with 6% moisture content DOT 4 fluid will not boil till about 150deg C.
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It depends on so many factors it is hard to quantify, I had the brake disks and pads replaced with Ford OEM parts back in 2005 and in 2017 I have covered over 143,000 miles and they have not been changed. I tend to be gentle on the brakes and on the last service it was reported the pads had 40% wear left on them. So many variables involved such as quality of the items and usage etc.
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I would say it's got nothing to do with washing the wheels (unless you are using neat phosphoric acid on a weekly basis) but is 99% to do with driving style.
I brought a 12 month old Subaru Legacy (approx. 10,000 miles) a few years ago, but not from a local dealer. When I booked it in for a service at 20,000 miles at somewhere closer to home, the service manager warned me I would probably need new front discs and pads! Needless to say it didn't ned them and when I sold it a couple of years later with 70,000 miles on the clock it still had the original discs and pads all round.
I would say I average about 80 - 100,000 miles on a set.
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I would say it's got nothing to do with washing the wheels (unless you are using neat phosphoric acid on a weekly basis) but is 99% to do with driving style.
I brought a 12 month old Subaru Legacy (approx. 10,000 miles) a few years ago, but not from a local dealer. When I booked it in for a service at 20,000 miles at somewhere closer to home, the service manager warned me I would probably need new front discs and pads! Needless to say it didn't ned them and when I sold it a couple of years later with 70,000 miles on the clock it still had the original discs and pads all round.
I would say I average about 80 - 100,000 miles on a set.
Not just driving style but usage pattern - the vast majority of my mileage is done on long runs, always off-peak so rarely any congestion - I'm close to the motorway network so I can drive all day braking only to stop for a rest break. Inevitable my pads and disks last a very long time, usually still on the car when it's eventually sold at 8-10 years old.
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John Im afraid I dont agree with your ascertion that brake fluid wont get moisture into it. We measure the moisture content of brake fluid on a service at the master cylinder and I can assure you brake fluid does accure water over time. A recent service for example on rear brakes on a mk 3 mondeo without the hydraulic system being opened up saw an ingress of air pass the rear caliper seals when the wind back tool was used resulting in a bleed required. My point is the issue on mondern brake fluid (DOT 4 is not the reduced boiling point as most people and car usage will not reach the boiling point of even heavily moisutre laden DOT 4. Its the corrosion effects to the alloys used in the calipers brought on by water entering the system). I'm speaking from many years of experience of running a garage. No we dont change brake fluid every two years as for example as recommended by BMW but when the moisture content exceeds 2%. We advise customers of the value recorded with our recommendations. It is up to the customer whether or not they have the work done. Incidently we take moisture in brake fluid seriously and avoid leaving fluid in open containers in the garage for this reason. I would NOT classify our garage as unscrupulous or ignorant just careful diligent and cognitive of the fact that most of the driving public today have less vehicle maintenance knowledge than they parents had due to the fact the modern motor car outwardly is far more reliable than those of 30-40 years ago and people simply dont tinker with their vehicles on their driveway on a Sunday in the way our Dads did
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. A recent service .... on rear brakes on a mk 3 mondeo without the hydraulic system being opened up saw an ingress of air pass the rear caliper seals when the wind back tool was used resulting in a bleed required.
This does not make sense. How does pressing a piston back force air past the piston seal?
My point is ... not the reduced boiling point ......Its the corrosion effects to the alloys used in the calipers brought on by water entering the system).
I contend caliper corrosion from damp brake fluid hardly ever happens. For one thing, it never gets damp enough, and also oxygen is required for corrosion. I have never ever had to change a disc caliper - even on our old 240,000m Passat. The ones on our Focus are 17yrs old, and TR7's are 37yrs old (although it had new rear cylinders a few years ago).
Caliper cylinders are far more likely to corrode when they are NOT bathed in old brake fluid, i.e. when garages needlessly change discs and pads before they are fully worn so the piston is always at the top of its travel. The cylinder surface is thus exposed to a thin layer of damp air (the piston wall cannot provide an airtight covering to the cylinder surface because it has to move) protected only by its hopefully airtight rubber boot, but over time and usage there is inevitably some exchange of air.
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